4.5.9.a Cams
Cams are manufactured as one piece with the shaft. However, there are prefabricated designs when the cams are pressed onto the shaft. Four-stroke engines, depending on the number of valves, have two or more cams for each cylinder: intake and exhaust. Cam shape ensures smooth lifting and lowering of the valve and the corresponding duration of its opening. Cams of the same name for each cylinder (for example, intake cams) are located in four-cylinder engines at an angle of 90 °, in six-cylinder engines - at an angle of 60 ° and in eight-cylinder engines — at an angle of 45 °. Opposite cams (intake and exhaust) are set at an angle, the value of which depends on the valve timing. The tops of the cams are located in the order of operation accepted for the engine, taking into account the direction of rotation of the shaft.
Figure 4.18 Cylinder head with camshafts.
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